HN user
When I work with multiple parallel sessions I take the time to plan things out first, and then run everything. This takes a bit off the cognitive load you're talking about, as you probably just have to answer some simple questions when the agents are working.
I haven't used Gemini CLI, but when I'm using Claude I use Opus for planning, and Sonnet for executing things. I barely use Haiku, but I sometimes use it for brainstorming or really simple tasks.
It's very addictive. It's so addictive that I'm constantly busy with coming up with new features for the different apps I have. I really have to plan time off. It's satisfying because I know how much work it would've cost me if I had to develop things myself. Seeing Claude Code finish things in hours or even minutes is really cool.